In general, radio frequency power control circuits for radio frequency power amplifiers are designed to switch rapidly from an un-biased (non-amplifying) state to a biased (amplifying). During this switching it is a requirement of the European Telecommunications Standards (ETS) specification that splatter must not occur. Splatter is essentially a power spectral re-growth that spills over to an adjacent channel frequency.
Typically, to avoid splatter, conventional radio frequency power amplifier control circuits typically employ a directional coupler, attenuator and a log amplifier biasing the power amplifier. There are significant size and cost overheads for the design and use of the directional coupler at the lower frequency VHF band. Furthermore, adjustment of the attenuator is necessary in order to fit the log amplifier operation into a log conformance's region as will be apparent to a person skilled in the art. Accordingly, the log amplifier limits the dynamic range of the power amplifier and adjacent power channel ramping cannot be switched abruptly or splatter will occur. Consequently, conventional radio frequency power amplifier control circuits employ a holding voltage of about 500 μSeconds that slows down the switching of the power amplifier from an un-biased (non-amplifying) state to a biased (amplifying).
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